1. Field of the Invention
This application relates generally to steering columns, and more particularly to adaptive energy absorbing devices for collapsible steering columns.
2. Description of Related Art
Automotive steering columns are typically equipped with kinetic energy absorption devices to reduce injury of a vehicle operator in the event of a collision that may cause the operator to impact the steering wheel. Such impacts during vehicle collision typically cause the steering column to collapse thereby absorbing energy that may otherwise be transmitted to the operator.
Such energy absorbing steering columns generally include a housing that translates linearly through a collapse stroke during a collision. A force generated by the driver from an impact with the steering wheel initiates the collapse stroke. The steering wheel housing moves against a resisting or reactive force that may be produced by an energy absorber designed to convert a portion of the driver's kinetic energy into work. The resisting force may be generated utilizing systems currently known in the art, including the plastic deformation of a metal element that is a part of an energy absorbing device.
Such energy absorbing (E/A) devices presently have fixed energy absorption capabilities, and offer no control over their performance during the collapse stroke. Typically, the resisting force against which the column is stroked is provided by plastic deformation of a metal element which comprises a part of the E/A system.
Generally, traditional energy absorbing devices have a fixed energy absorbing curve which is optimized to protect a given group of drivers, in most cases represented by an average size male driver. To better protect other groups of drivers not belonging to the average male driver group, such as smaller female drivers or large drivers, an adjustable energy absorbing device is needed in the art. It is also desirable for E/A devices to have performance characteristics that can vary upon factors other than driver size, such as his or her position and the speed of vehicle.
It is, therefore, desirable for an energy absorbing device to be adjustable based upon a given driver size and his position, as well as include variables for the severity of the collision. It is also desirable to use an energy absorbing device that is capable of adjusting in a time frame similar to that of an airbag system. Therefore, to account for the severity of the collision, and act at the same time as an airbag, an energy absorbing device should be capable of adjustment within a few milliseconds of time such that a given load curve can be utilized by the device based on the severity of the collision and the characteristics of the driver.
There is, therefore, a need in the art for an active energy absorbing device that is capable of automatically adjusting performance characteristics to account for the severity of a collision, as well as the characteristics of the driver; and to do so within a workable time span (i.e. a few milliseconds) and similar to that of an airbag deployment.